Presently, image-forming apparatuses, such as, for example, digital copying machines, are introduced into the market. In the digital copying machines, a document image is copied as follows: First, the image-reading section reads the document image. Then, the image-processing section carries out specified image-processing on the read document image. Thereafter, the recording section printouts image information which has been subject to the image processing. Therefore, in the digital copying machine of this type, an image is copied onto a sheet of paper by using only the image-processing functions that are provided in the particular digital copying machine.
Here, in recent years, it has been proposed that a plurality of image-recording apparatuses or other apparatuses be organized into a network. For example, Japanese Laid-Open Patent Publication 116834/1978 Tokukaishou 53-116834) discloses an arrangement wherein a plurality of image-reading apparatuses and a plurality of image-recording apparatuses are connected through a control section.
In such an arrangement, an original image that has been read by any of the image-reading apparatuses is printed by any of the image-recording apparatuses. This arrangement makes it possible to shorten the stand-by time of the image-recording apparatus that is caused by processes, such as an exchanging process of originals in the image-reading apparatuses.
Moreover, Japanese Examined Patent Publication 36592/1995 (Tokukouhei 7-36592) discloses an image-forming system wherein a plurality of copying machines, each having an image-reading section and an image-recording section, are connected to a control device. In this image-forming system, an image signal that is to be recorded is supplied to the copying machines in a distributed manner in accordance with a document copying mode that has been set, and copying operations are carried out by the copying machines in parallel with one another.
However, the conventional image-forming systems have the following problems.
Presently, various image-processing functions in the digital copying machine are dependent upon software. Here, with the recent remarkable developments of the software, the image-processing functions have been highly improved in a very short period, and new copying machines having additional unprecedented functions have been newly introduced into the market. Consequently, even when a digital copying machine having desired image-processing functions is purchased, the digital copying machine, which has the highest image-processing functions at the time of the purchase, will soon become outdated with relatively low functions in a short period.
In this case, it is impossible for the purchased digital copying machine to obtain functions higher than those originally provided in the digital copying machine. In the case when higher functions or newer functions are required, it is inevitable that a new copying machine has to be purchased to replace the older one. This tends to impose a big burden on users on an economic basis, and also to present an inherent problem for makers that try to provide consumers with new merchandise.
In order to solve these problems, an image-forming system in which, for example, the following processes are carried out has been proposed; this system will eliminate the need for the purchase of a new machine, and will provide an optimal system. In other words, any of the copying machines reads a document image, and the read document image is subject to image processing by another copying machine. In this case, processed image information, obtained from the copying machine that has carried out the image processing, is again returned to the copying machine or other device which read the document image. Then the copying machine in question printouts the processed image information.
In contrast, the aforementioned prior art system has a problem in that, although the copying machine which has carried out image processing can printouts the processed image information, the copying machine or other device which read the document image cannot printout the processed image information returned again thereto.
Moreover, when desired image processing is carried out by the current machine, the amount of processed image information sometimes becomes larger than that of the image information before the image processing. Therefore, in the case when image information is transferred to a plurality of machines, and image processing is carried out by using those machines in a combined manner, if image processing is carried out indiscriminately in the current machine, it sometimes takes a lot of time to transfer the image information. Furthermore, since the respective machines have their own degrees of image-processing performances, if image information is transferred to a certain machine indiscriminately, the image processing rather tends to take longer. The resulting problem is an inefficiency of the entire image-forming system.